Phono preamp tube rolling.

Mullard Blackburn longplates are very good. I also like the CV4003 boxplates, although the 12AU7 long plate square getter and large O-getter are cleaner sounding with excellent imaging.

I love the Brimar CV4003 boxplates, similar but more  transparent than Mullard with very good highs.

For phonostage I mostly used 1950's RCA black plates. Not as warm as Mullard. More transparent with great dynamics. Need to request low-noise.

By the chance, did anybody tried Japanese stuff? ….Hitachi 12AX7, NEC 12AU7, Toshiba 12AX7 or Matsushita 12AX7 ?

Rolling some 12AX7 tubes in my Sun Valley phono pre. I found the Genalex Russian tubes to be way too bright and glaring. Brent Jesse turn to be on to some RCA vintage gray plates and those were pretty perfect. My music is mostly rock and roll. Jazz and classical folks might go with something a bit more nimble and musical like Siemens or Telefunken.